Propagation of Seabuckthorn
The most common methods for propagating seabuckthorn are by seed, softwood or hardwood cuttings, and layering and suckers. Micropropagation using meristem culture is now readily available as well.
Propagation from seed is relatively simple and produces a large number of seedlings at fairly low cost compared with other propagation methods. Long term storage affects seed viability, up to 60% after 4 – 5 years. Prior to sowing, the seeds should be soaked in water for 48 hours, discarding any floating seeds. For early spring direct seeding, seeds are seeded at soil surface and irrigated periodically to prevent seeds from drying out. If seeding in the late spring, seeds should be covered with very light layer of soil. Seeds should start to germinate within 5 – 10 days based on the condition of the seeds and the species of seabuckthorn. Seabuckthorn seeds can be seeded indoors in pots in January or early February, one seedling per pot is allowed to grow for 3 months before transplanting to the field in early May. All other methods produce plants identical to parent.
Cuttings produce rooted plants with the same genotype as the parent plant. The cuttings will bear fruit 1 – 2 years earlier than seed-propagated trees. Seabuckthorn can be propagated using either hardwood or softwood cuttings.
Hardwood cuttings should be chosen in Jan. – Feb. from healthy, well developed plants in fruiting stage, so the sex can be determined. Cuttings (15-20cm long) should be taken from the previous year’s growth during dormancy in the early spring. Bundles of cuttings are soaked in water (room temperature and changed once a day) and covering 2/3 of their length until the beginning of formation of roots. Cuttings can also be treated with IBA (50mg/L) or rooting hormone and placed in pots filled with peat in a bottom heated propagation box (15-20C). Cuttings can be transplanted when the roots are 1-2 cm long directly to the field. A softwood cutting (15-20cm long) from sexed trees are taken when shoots begin to become woody, remove the lower leaves, leaving 2-4 leaves at the tip and dip into rooting hormone before rooted in media such as sand or perlite and keep special attention to the moisture of media. Rooted should be planted in pots for 1-2month before transplanting to field. Root cuttings also can be an effective propagation method for seabuckthorn. Root cuttings were planted in pots and placed in a greenhouse for six weeks before being transplanted to the field at a spacing of 8x20cm. Cuttings need to be acclimatized to field conditions prior to planting by placing pots in a shady area for one week. The best results were obtained in sandy loam at pH 6-6.5 with medium humus content. Seabuckthorn easily produces suckers within a few years of planting which is a good source for propagation of plants where the sex is known. Make sure you get the proper ratio of male and female plants within each plantation.
In the last few years techniques have been developed for the micropropagation of many plants, including seabuckthorn and they are now available commercially. This process, like cuttings and suckering, give plants identical to the parent, while seeds do not.
In its natural environment, seabuckthorn plants are found on slopes, riverbanks, and seashores in a wide range of soil texture. Soil acidity and alkalinity, except at extreme levels, are not limiting factors, however, the most favorable range is pH 5.5 – 7.0. If the soil pH is too low, it can be corrected by application of lime such as dolomitic limestone.
When planting seabuckthorn in arid or semi-arid areas, water must be supplied for establishment. It can tolerate a little drought, but it is a moisture sensitive plant especially in the spring when plants are flowering and starting to set fruit. It can not tolerate high levels of ground water, therefore situating plants on soil with good drainage is essential. The optimal soil moisture for seabuckthorn is around 70%.
Just like any other crop, seabuckthorn requires adequate soil nutrients for a high yield with good quality. It responds well to phosphorus fertilizer, especially in soils low in phosphorus. Manure or compost can also be applied before planting. Remember that seabuckthorn is a nitrogen fixing plant.
Spring is the best time for planting seabuckthorn. A spacing of 2m between the trees is recommended. Rows should be oriented in a north-south direction to provide maximum sun exposure.
Since seabuckthorn is a dioecious shrub, male and female plants have to be adequately maintained. The ratio of male to female plants should be from 1:4 to 1:6. If seedlings of unknown sex are planted, it will approximatelly result in a 53/47 distribution of male and female plants within each planting.
The purpose of pruning seabuckthorn is to train branches, promote growth and facilitate harvesting. Seabuckthorn may grow up to 2-3 m in four years. The trees should be pruned annually to remove overlapping branches, and long branches should be headed to encourage development of lateral shoots. Mature, fruiting plants should be pruned to allow more light penetration if the bush is dense. To prevent seabuckthorn from premature senescence, three year old branches should be pruned in the early winter for rejuvenation.
Weed control is very important in seabuckthorn plantings. Proper weed control promotes growth of newly planted seedlings. Cultivation in new plantings should not disturb the soil 8-10 cm below the surface so that shallow roots are not damaged. In an orchard planting, it is ideal to have row covers such as grass between rows to enable harvesting and reduce erosion. Mulches between trees within the row will reduce the cost of weed control and keep soil moisture and temperature to promote better growth.
Seabuckthorn has had relatively few pests reported. Of the insects, the most damaging is the green aphid (Capithophorus hippophae).